Waterproofed parchment-paper



UNITED STATES PATENT O EIcE.

EMERY ANDREIVS, OE KENNEBUNK, MAINE, ASSIGNOR TO THE LEATHER- V OID MANUFACTURING COMPANY, OF MAINE.

WATERPROOFED PARCHMENT-PAPER.

SPECIFICATION forming part of Letters Patent No. 458,840, dated September 1, 1891.

Application filed March 8, 1889. Serial No. 302,523. (No specimens.)

To all whom, it may concern.-

Be it known that I, EMERY ANDREWS, of Kennebunk, in the county of York and State of Maine, have invented anew and useful Im- 5 provement in Waterproofed Pachment-Paper, of which the following is a specification.

My invention relates to an improved parchmentized paper-board.

Heretoforep ellulose usually in the form of paper, has been treated by immersion in a bath of sulphuric acid, chloride of zinc, or other parchmentizing-liquid, the action of which transforms the paper into what isknown as vegetable parchment, vulcanized fiber, or leatheroid. This product while possessing many valuable qualities has others which are objectionable, such as its susceptibility to the action of moisture, which softens and swells it and renders it unsuitable for many purposes to which it might otherwise be applied, and which is difficult to overcome by reason of the impermeable nature of the ma terial to the usual waterproofing liquids, such as oils, or solutions of gums or resins.

5 The object of my invention is to produce a material which, while possessing the valuable properties of such products, shall be of greater flexibility and more permeable to oils and other liquids, with which it is desirable under certain circumstancesto permeate itgcfand it consists of a material composed of parchmentized cellulose and containing finely distributed all through its substance asbestus, or an equivalent fibrous mineral not acted upon by the liquid which served to parchlnentize the verized cellulose (which is usually in the form of paper-pulp) from twenty-five to sixty per cent. of its weight of asbestus, and when the same has been thoroughly ground and mixed with the paper-pulp, the mixture is run into paper in the usual way, and the paper is thus parchmentized by any of the known processes, such, for instance, as is set forth in Letters Patent of the United States granted to T. and T. S. Hanna, No. 198,382, dated December 18, 1877. As such paper is parchmentized, it may be made into board of any desired thickness by the well-knownprocess of winding it about a cylinder under pressure until the desired thickness is obtained, when the tube of paper sistingof parchmentized cellulose and a min- 

